As is known, a flaying machine (or machine for membrane removal) comprises a frame supporting a flat top on which a piece of meat to be flayed is placed; the flaying machine is equipped with a toothed roller that is set into rotation by a motor and drags the piece of meat, which is manually retained by the operator, so as to submit it to the action of a blade for the purpose of separating the rind from the flesh.
The operator moves the piece of meat close to the roller that automatically drags the product, but his/her hands are working in the vicinity of the roller and the blade.
During operation, the risk of accidental contact of the operator's hands with the blade exists, due to inattention or various unforeseen events that can cause sudden and involuntary movements of the operator's hands resulting in unexpected contact with the blade.
For these reasons, flaying machines can be provided with electronic systems designed to protect the operator's safety.
Yet, a drawback of these systems is that system intervention sometimes takes place even in the absence of real danger, thereby giving rise to the undesirable stopping of the machine resulting in delays in production and reductions in work time.
During operation, there is also the risk of accidental contact with the hands of persons in charge of other tasks, and although they do not specifically work with the flaying machine, they may find themselves having to walk or perform functions in the vicinity of the machine itself.
To mitigate this problem, in Italian patent No. 0001262331 the same Applicant discloses a safety system for a flaying machine using as the critical parameter of detection of an alarm situation, the drop in voltage between the flaying machine and the earth, as compared with a reference signal; the latter, however, cannot be easily estimated as it is affected by the electro-physical characteristics of the operator in charge of the machine and by the environmental conditions, such as moisture and temperature.
An improved solution to the problem is shown in the European patent application no. 10178838 by the same Applicant, wherein the system subjects the working machine to electric oscillation by means of a circuit-related solution. The frequency is equal to that of the resonant circuit; each “touch” of the operator affecting this circuit causes a disturbance to the resonant circuit. Should this disturbance prove to be excessive, the continuously monitored safety system disables the machine.
This system requires a specific pre-operative calibration sequence for identification of the human parameters of the operator so that the machine will react in the case of an alarm based on personalized settings regarding the user, so as to guarantee the safety of the same user.
This system requires the utilization of a computer display for management of the calibration procedures and supplementary electronic marking so as to enable univocal identification of the operator who is qualified for use of the machine.
Furthermore, operation of the system is still not completely immune to environmental conditions in the presence of particular levels of moisture and particular temperature ranges.
These issues are essentially due to wear of the gloves both the conductive and the insulating glove of the operator.
Moreover, poor care of the gloves, both the conductive and the insulating glove, on the part of operators is frequent and it is not rare to see operators working with gloves that are unsuitable electrically, although they may be intact on the outside.
The operator often tends not to replace obsolete gloves with sufficient frequency.
That which has been described makes improvement of the safety of the operators even more important.
The published patent application EP0445860 filed by the same Applicant discloses a control and safety system for electrically operated devices with a cutting tool connected to an electric motor, and control means for halting and reversing the movement of the motor.
The system comprises a pair of electrically conducting gloves to be worn by the operator and connected by a conducting wire to a control box fixed to the operator's body and containing a rechargeable battery and an electronic sensor-transmitter circuit designed to emit a light pulse when both gloves are being worn by the operator and to interrupt the light pulse when one of the two gloves or part of the operator's body accidentally makes contact with any metal part of the device; an optical fibre is suitable for connecting the control box to the base of the device, in which a receiving control circuit is located.
The solution provided necessarily requires a physical connection optical fibre between the control box worn by the operator and the device (the machine to be controlled).
A solution such as this hinders the operator, who remains physically bound to the machine and is not totally free to move.
Furthermore, the technology utilized is useless and complex to realize.
The aim of the present invention is to provide a safety system for working machines that is improved in terms of safety for an operator.
Another aim is to provide a safety system that is simple to implement and realize.
A further aim is to provide a safety system that is operatively easy to use.
An additional aim is to provide a safety system that is capable of ensuring quick identification of the operators.